A recently isolated maize transposable element, Mul, has been used to generate new mutants. We propose to use rapid screening methods to recover mutants deficient in one or more photosynthetic activities or groups of functionally related proteins. Further characterization of selected mutants will allow us to concentrate on those whose gene products appear to regulate the synthesis or assembly of photosynthetic complexes. Since the mutants were caused by Mul insertions, a Mul probe will be used to isolate mutants by molecular cloning. The role of the cloned genes in synthesis or assembly of multiprotein photosynthetic complexes will be determined.